基于平均距离聚类的NSGA-Ⅱ

拥挤度距离是一种用于度量解集多样性的指标. 然而, 在许多情况下, 该指标无法有效区分多样性较优个体. 其原因为拥挤度距离主要利用每个位置的局部信息. 为解决该问题, 基于整个种群全局位置信息, 本文设计了基于平均距离聚类的多样性度量指标, 并进一步提出了基于平均距离聚类的NSGA-Ⅱ. 该算法利用平均距离将种群划分为若干个大致均匀分布的小种群, 然后分别在各小种群内执行选择、交叉和变异等操作. 实验结果表明, 本文所提算法可以有效地保持种群多样性.     

信号配时对交通排放影响的仿真分析及优化

以新乡市典型平面交叉口——平原路与劳动路交叉口为例,借助于仿真软件,真实再现了交通流运行情况,从定量的角度分析信号配时对交通排放的影响,并提出两种解决方案,为改善该交叉口交通环境恶劣和交通拥挤提供了切实可行的依据。     

小世界模型的个体决策微粒群算法

微粒群算法是一种模拟动物行为的群智能优化算法.由于微粒(个体)在不同环境中生存与觅食,积累了不同的经验,因此不同个体在觅食或者其他行为中会做出不同的决策,但是这种决策机制在标准微粒群算法中并没有体现出来.微粒在决策时会考虑周围其它粒子的信息,因此本文通过引入个体决策机制与小世界模型的邻域结构来改进微粒群算法,同时利用李雅普诺夫稳定性理论对改进的算法进行稳定性分析,并给出相应的参数选择方式.在改进的微粒群算法中,微粒被周围理想微粒的位置和群体最优位置所吸引,改变了传统微粒群算法只被群体最优位置吸引的弊端.对常用的几个测试函数进行仿真,与其它两种改进的微粒群算法相比,结果表明该算法有更好的性能.     

柔性车间调度的解空间距离聚类和变邻域搜索粒子群算法

根据柔性车间调度问题提出基于解空间距离聚类和变邻域搜索的粒子群算法.在粒子群算法基础上采用贪婪策略引入变邻域搜索方式,即调整关键路径上最大关键工序的机器位置,调整关键路径上工序相对位置变化,加强局部搜索能力;根据机器加工工序的空间距离,采用K-means聚类得到机器加工工序“优良个体”,加大局部搜索性能.同时对于粒子群算法速度更新采用局部停滞策略,保留局部片段相对位置不变特性.通过实验仿真,优化算法取得了较好的效果,与一般的粒子群算法相比较收敛速度迅速且性能良好.     

毛用反应性紫外线吸收剂的应用性能

将自制的反应性苯并三唑类紫外线吸收剂UV-WR单独或与Lanasol活性染料同浴上染羊毛织物。结果表明,经毛用反应性紫外线吸收剂UV-WR上染的羊毛织物具有较好的紫外线防护效果,并且具有一定的耐洗牢度。与染料同浴上染时,紫外线吸收剂UV-WR和Lanasol活性染料对羊毛的上染率、固色率都略有下降,两者间表现出一定的竞染作用。     

以工作过程为导向的汽车发动机电控系统与维修课程教学改革

汽车发动机电控系统与维修是汽电专业的核心课程,如果课程内容脱离实际,教学方法重理论轻实践,就很难达到培养目标。文章通过对汽电专业毕业生从事的职业岗位群进行分析,根据岗位所要求的职业能力和职业素养,分解工作任务,设计教学内容,改革教学方法,完成教学评价。     

一种求解连铸生产调度问题的非线性遗传算法

在对连铸生产工艺背景及工艺约束进行分析的基础上,以使所有连铸机上组成每一个浇次的炉次之间因差异引起的费用最小为目标函数,构造了最优浇次的数学规划模型,并基于该模型,提出了先将所有待优化的炉次聚类成若干个浇次(浇次数已知),然后对每个浇次应用基于Tabu搜索的非线性遗传算法,仿真结果表明该算法的有效性。     

Research progress on chemical modification of silk fibroin and its applications北大核心CSCD

Mulberry silk is composed of the two major parts of two triangle-like silk fibroin fibers and sericin covering the fibers and a few lipids. After removing the sericin on the raw silk what is left is the silk fibroin fiber. Silk fibroin is the main part of silk accounting for about 75% of the total weight. Silk fibroin contains 18 natural amino acids such as glycine Gly alanine Ala serine Ser serine aspartic acid Asp and tyrosine Tyr . The secondary structure of silk fibroin has three main conformations α-helix β-fold and random coil. Under certain conditions the three conformations can transform into each other and change the mechanical properties of the silk fibroin material. Silk fibroin extracted from silk fiber is a natural polymer with biocompatibility and biodegradability. It can be further processed into different forms of materials nanoparticles films hydrogels sponges etc. It has been applied in many fields such as biomedicine and cosmetics. In order to meet the needs of different fields researchers have conducted further chemical modification treatment based on the original excellent properties of silk fibroin. Meanwhile the active groups on various amino acid residues in silk fibroin also provide chemical reaction sites for the chemical modification of silk fibroin. The chemical modification methods of silk fibroin mainly include amino acid residue modification macromolecular grafting modification and crosslinking reaction modification. Among them amino acid residue modification can modify protein amino acid residues by chemical reagents and some groups can be introduced into the side chains of silk fibroin macromolecules. Grafting modification of silk fibroin macromolecules is one of the main means to bind functional compounds to silk fibroin macromolecular chains. The properties of grafted silk fibroin are affected by the type and grafting rate of the grafts. The chemical crosslinking reaction modification of silk fibroin macromolecules is to make the macromolecular chains connected by covalent bonds and form a network structure by means of crosslinking agents enzymes or ultraviolet irradiation. The cross-linking reaction can not only form covalent bonds within and between the molecular chains of silk fibroin thus changing its structural properties and improving its stability but be used to form covalent bonds with other polymers. At present the chemical modification of silk fibroin is mainly applied in the fields of silk textiles biomedicine and environmental science. In the field of silk textiles graft copolymerization modification of vinyl and other monomers crosslinking agent modification and other methods are used to overcome the shortcomings of silk like being easy to wrinkle. The graft modified monomers mainly include ethylene methacrylate and methylacrylamide. The active groups on crosslinking agents such as polycarboxylic acid / anhydride and epoxide are covalently combined with carboxyl hydroxyl and amino groups on macromolecules of silk fibroin to improve the wrinkle resistance of silk fabrics. In the field of biomedicine silk fibroin materials with appropriate chemical modification have better biological activity drug delivery ability antimicrobial properties and mechanical properties. The optimization of these properties enables silk fibroin materials to show great potential in drug control delivery tissue regeneration and wound repair. The applied research in the field of environmental science mainly focuses on the adsorption separation and catalysis of impurities in water. Therefore the modification of amino acid residues grafting and cross-linking of protein macromolecules can change some important properties of silk fibroin and meet the requirements of various applications and functionalization of silk fibroin. In many fields of chemical modification and application of silk fibroin protein fruitful results have been achieved which has laid a good foundation for the further development of related fields and also shows that the chemical modification of silk fibroin material has great potential and application prospects. However there are still some problems that need to be overcome and further improved in the current chemical modification methods such as mild modification conditions and accurate adjustment of the degree of modification which will be the research direction of related fields in the future. © 2022 Authors. All rights reserved.     

一种求解数值优化问题的非线性遗传算法

由于算术杂交算子的线性搜索范围及变异算子的随机搜索，导致了实数遗传算法的效率较低．为此，通过拓展遗传算子的搜索范围，提出了一种动态双层非线性杂交算子，并将混沌搜索引入变异算子，从而给出了一种求解数值优化问题的非线性遗传算法．实例仿真证明该算法的有效性，并以“平均截止代数”和“平均截止代数分布熵”作为评价指标，对该方法的优化效率进行了研究，定量的评价了该方法的优化效率，通过与实数遗传算法进行比较，进一步说明了该方法的优化效率高于实数遗传算法。     

改进蚁群算法在机器人路径规划中的应用

机器人路径规划是机器人技术研究中的一项关键技术。针对蚁群算法在求解机器人路径规划中准确性不高以及求解时间长的问题,提出了一种基于改进蚁群算法的机器人路径规划方法,采用栅格法构建了相应的数学模型。为了提高蚁群算法的全局搜索能力,防止算法早熟收敛,在状态转移规则中引入了随机策略;同时引入了基于狼群分配的策略来更新启发式信息,这样可以进一步提高算法的收敛速度。实验结果表明,改进的蚁群算法具有更强的全局寻优能力,求解时间更短,它可以有效地求解机器人路径规划问题。